Process for the production of non-woven elastic polyurethane fabric



United States Patent Int. (:1. D01f 7/56,- D06m 3/24 U.S. Cl. 264210 4Claims This application relates to the production of filament material,and more particularly to the production of fabrics from filaments,especially non-woven fabrics.

This application is a continuation-in-part of application Ser. No.341,489, filed Jan. 27, 1964, and the disclosure of the said co-pendingapplication is incorporated herein by reference.

Ser. No. 341,489 discloses a process for spinning of filaments whichcomprises issuing a fused polymer mass in the form of filaments fromseveral linear rows of spinneret holes of a spinneret head, anddirecting gas streams into impinging and entraining relation with theissuing fused polymer filaments to draw them and orient polymermolecules in the direction of the filament axis. The mass is drawn toreduce the diameter from the diameter of the spinneret hole in the ratioof at least 30:1, and the filaments are cooled to a set conditionwherein the molecular orientation is retained. The filaments aremaintained in drawn condition during the cooling by gas streams directedagainst the filaments to urge them to the drawn condition. In practicalapplication, a multitude of linear, parallel filament rows aresimultaneously drawn while keeping them in parallel arrangements withinseparate air channels, and the drawn and set filaments of the dilferentrows are finally collected on a screen or perforated roll for theformation of a fleece or mat.

It has now been found that the process of Ser. No. 341,489 canadvantageously be utilized in the production of filaments frompolyurethane. If a melt of polyurethane which is not cross linked or notcompletely cross linked is utilized in the process, and cross linking ispermitted to occur during the drawing of the fused polymer issuing fromthe spinneret head, filaments, and in turn fabrics, characterized byuniformly high elasticity are obtained. Macro diisocyanate polyesters orpolyethers containing glycols or diamines in an amount desirable for theintended cross linking, can be used. The moisture present in the airwhich is blown along the path of the fused polymer can be relied upon tocause the cross linking to occur.

Apparatus as is disclosed in Ser. No. 341,489 can be used in thepractice of the instant invention. Thus, apparatus as is shown in Fig.of the drawing of the prior application can be used. Accordingly, theapparatus can include a plurality of parallel disposed nozzles, eachhaving in excess of 100 holes of about 0.4 mm. diameter at a spacing of2 mm., in a straight line. An air slot of 0.3 mm. width can be providedon each side of each line of spinneret holes at a spacing of 0.5 mm.from the line of holes. The nozzles can be heated to the temperature ofthe polyurethane melt or to the desired reaction temperature, and airheated to the same temperature can be blown through the slots to providethe desired drawing of the fused polymer. The air velocity leaving theslots is at least five times greater than the velocity of the threadsissuing from the spinneret holes. The nozzles can be spaced about 60 mm.apart. At least about mm.

3,439,085 Patented Apr. 15, 1969 from the nozzles, in the direction ofadvance of the fused polymer, guide passageways are disposed. There is aguide passageway for each nozzle made up of a plate disposed above theplurality of filament forms and a plate disposed below the filamentforms; the spacing of the plates is about 50 mm., and the passageway is600 mm. in length (in the direction of travel of the filaments); thepassageways terminate in the lateral direction about 10 mm. from theoutermost filament form on each side. Air can be injected into thepassageway through the plates, the air being injected from above andbelow the filaments. If desired, the guide passageways can be moved asis indicated in Fig. 8 of Ser. No. 341,489, in a rocking motion, toimpart a corresponding movement to the filaments. The filaments can becollected on a drum or conveyor as is disclosed in Ser. No. 341,489.

If desired, filaments of different composition can be combined in asingle fleece, using different nozzles for the different filamentcompositions. For example, a fabric could be formed of polyurethane andpolyamide fibers.

The fibers when they are deposited on the collecting means wherein theyare gathered into a fleece, can be in such condition that bonding offilaments occurs at filament crossing points. In this manner a bondedfleece can be obtained without the addition of binding agents. Suchprocessing finds application where the fibers are all polyurethanepolymer, and also where the fibers are mixtures of filaments ofdifferent composition, such as polyurethane and polyamide.

The invention is further described in the following examples.

Example 1 A granular polymer composition of parts of a condensationproduct of adipic acid ethylene glycol polyester and diphenylmethan-4,4'-diiso-cyanate, partially crosslinked with 30 partsbutane-1,4-diol was melted in a wormpress at a temperature of 180 C. andsupplied at a temperature of 200 C. to four spinning pumps. Thespinning-pumps conveyed the melt to four spinning nozzles openingdownwardly and heated to 205 0, arranged parallel to one another at adistance of 80 mm. apart. Each of the spinning-nozzles consisted of astraight line of holes of 400p. diameter, spaced apart 2 mm. so thateach of the four longitudinal nozzles had a straight row of holes of 320mm. length. An air slot was positioned on both sides of each line ofholes. The slots were 3 mm. x 340 mm. length, and were spaced .5 mm.from the holes. Air heated to 205 C. with a pressure of 0.8 atmospheregauge was supplied to the slots so that from both slots a band-shapedair-stream of about 340 mm. width issued. From the row of holes, inturn, issued a series of still melted polyurethane filaments, which atboth sides were pulled forward by the band-shaped air streams, issuingwith a velocity of about 5000 m./min. Therein the filaments were drawnfrom a cross-section of 400 to about 30;/.. Since the filaments werevery viscid, and would upon touching at once stick together, turbulenceformed through friction of the adjacent air-layers, had to be excluded.For this purpose, the thread group of each nozzle, together with theband-shaped air currents enveloping it was introduced into elongatedguide-channels, which were spaced 20 mm. from the nozzle bore holes. Theair channels had the following interior-measurements: 50 mm. platedistance, 340 mm. width, 600 mm. length. Additionally, the inner-wallsof each air channel were rinsed with further cold air-streams, with theaid of two air slots of 0.3 mm. slot-height in each wall, disposed atthe inlet and outlet side. The slots were at an angle of 10", so that anair rinsing impinged tangentially to the fiber flying direction. Thepressure used for the rinse air was 3 atmospheres gauge on the slots.Through these measures it was possible to prevent a mutual entangling aswell as touching of the individual filaments of each group. Since eachindividual nozzle had a channel allotted to it, the entangling of thethreads of adjacent nozzles was not possible. The fleece formation tookplace after the filament left the air channels. The fibers andair-streams were separated with the aid of a screen through whichsuction was applied. The screen was mounted at a distance of 700 mm.

. from the outlet end of the air-channels. The matting of the Example 2The apparatus of Example 1 was used, but nozzles 1 and 3 were suppliedwith the above-described polyurethane, and nozzles 2 and 4 were suppliedwith polycaprolactam. The Working conditions of the nozzle 2 and 4 wereas follows: nozzle temperature 230 C., air temperature 230 C. The fleeceformed contained, in the ratio 1:1, endless polyurethane and polyamidefilaments, bonded together at crossing points.

Whereas in the examples, moisture in the air is relied upon to cause thecross linking which occurs during drawing of the filaments, any otherknown suitable means can be relied upon for providing the cross-linkingconditions. In general, air at ambient conditions is suitable for thepurpose.

What is claimed is:

1. Process for the production of non-woven elastic fabric, whichcomprises fusing a cross-linkable polyurethane mass; melt-spinning saidfused mass into a multiplicity of substantially endless filaments;air-drawing said substantially endless filaments while maintaining saidfilaments in a hot and tacky state, whereby the molecules of saidfilaments are oriented in the direction of the axis of said filaments;laying said hot, tacky oriented substantially endless filaments on asupporting surface; cross-linkin-g said substantially endless filamentsby means of moisture in said air; and welding said substantially endlesspolyurethane filaments to other such filaments by means of itstackiness, wherein said filaments become solid and non-tacky after saidwelding.

2. Process according to claim 1, wherein simultaneously a second polymerof different composition from said first-mentioned polymer is drawn intofilaments in like manner, and the filaments of both polymers arecollected together to form the fleece.

3. Process according to claim 1, wherein the filaments solidify aftercollection thereof in crossing relation and become bonded together atcrossing points during the solidification.

4. Process according to claim 2, wherein the polyurethane filamentssolidify after collection of both polymers in crossing relation and uponsolidification filaments become bonded together at crossing points.

References Cited UNITED STATES PATENTS 2,810,426 10/1957 Till et al.51-295 3,026,190 3/1962 McMahon et a1. 51-295 2,336,745 12/ 1943Manning.

2,869,973 1/1959 Hubbard 16l--170 3,117,055 1/1964 Guandique et a1.161170 3,154,611 10/1964 Dinber'gs 2 64176 3,158,525 11/1964 Reynolds161-170 3,199,281 8/1965 Maerov et al 264210 2,411,660 11/1946 Manning264176 DONALD J. ARNOLD, Primary Examiner.

US. Cl. X.R.

1. PROCESS FOR THE PRODUCTION OF NON-WOVEN ELASTIC FABRIC, WHICHCOMPRISES FUSING A CROSS-LINKABLE POLYURETHANE MASS; METL-SPINNING SAIDFUSED MASS INTO A MULTIPLICITY OF SUBSTANTIALLY ENDLESS FILAMENTS;AIR-DRAWING SAID SUBSTANTIALLY ENDLESS FILAMENTS WHILE MAINTAINING SAIDFILAMENTS IN A HOT AND TACKY STATE, WHEREBY THE MOLECULES OF SAIDFILAMENTS ARE ORIENTED IN THE DIRECTION OF THE AXIS OF SAID FILAMENTS;LAYING SAID HOT, TACKY ORIENTED SUBSTANTIALLY ENDLESS FILAMETNS ON ASUPPORTING SURFACE; CROSS-LINKING SAID SUBSTANTIALLY ENDLESS FILAMENTSBY MEANS OF MOISTURE IN SAID AIR; AND WELDING SAID SUBSTANTIALLY ENDLESSPOLYURETHANE FILAMENTS TO OTHER SUCH FILAMENTS BY MEANS OF ITSTACKINESS, WHEREIN SAID FILAMENTS BECOME SOLID AND NON-TACKY AFTER SAIDWELDING.